The present invention relates in general to an end surface capillary structure of a heat pipe, and more particularly, to a heat pipe that includes end surfaces in contact with heat source to dissipate heat and a wick structure fabricated by power sintering and mesh woven.
Having the characteristics of high thermal conductivity, fast thermal conduction, light weight, non-movable components and simple structure, heat pipes are able to deliver large amount of heat without consuming electricity, and are therefore commonly used in the market.
FIG. 1 illustrates a conventional heat pipe 1a that includes a pipe member 10a and a powder-sintered wick structure 11a attached to an internal sidewall of the pipe member 10a. The wick structure 11a provides capillary force to transport working fluid filled in the pipe member 1a. However, the fabrication of the wick structure 11a requires an axial bar 12a inserted into the heat pipe 1a for supporting the wick structure 11a during powder sintering process to avoid powder collapse. This type of wick structure has the following drawbacks.
1. When the axial bar 12a is inserted into the pipe member 10a of the heat pipe 1a, it is difficult to dispose the axial bar 1a along the axis of the pipe member 10a. Instead, the axial bar 1a is easily deviated from the axis to cause non-uniform wick structure 11a, such that the fluid transportation is non-uniform to cause poor thermal conduction.
2. After powder sintering process, the powder for forming the wick structure 11a is easily attached to the axial bar 12a to cause problem for removing the axial bar 12a from the pipe member 10a. Therefore, the quality of such heat pipe depends on proficiency of the operator, and it cannot be fabricated by mass production.
3. As it is difficult to remove the axial bar 12a, external force is required for the removal. However, because an annealing process the wick structure 11a and the pipe member 10a are before being removed, the heat pipe 1a is extremely soft during the removal process. Therefore, the heat pipe 10a is easily deformed, the wick structure is easily damaged, and the dimension precision will be greatly affected.
FIG. 2 illustrates a cross sectional view of another conventional heat pipe 2a. The wick structure 21a attached to an internal wall of the pipe member 20a of the heat pipe 2a is fabricated by mesh weaving. The mesh woven wick structure 21a is easily bent and curled before being disposed into the pipe member 20a. Therefore, the woven mesh cannot be properly adhered to the interior bottom corners A to cause incomplete capillary transfer. That is, the capillary force is relatively weak, delivery of the working fluid is slower, and the heat conduction performance is poorer. If one forces the woven mesh completely attached to the internal surface at the bottom corners, the structure of the woven mesh will be discontinuous because of deformation and pressure to cause poor delivery of working fluid.
Therefore, there exist inconvenience and drawbacks for practically application of the above-mentioned conventional heat pipe. There is thus a substantial need to provide an improved end surface capillary structure of a heat pipe that resolves the above drawbacks and can be used more conveniently and practically.